Use symbols internally for postags and chunk tags.
Merge branch 'master' of git://github.com/knowitall/nlptools into headword
Merge remote-tracking branch 'origin/headword'
Take changes from knowitall/master into headword, and update aggregate in build file.
Merge branch 'master' of https://github.com/knowitall/nlptools into headword
Merge pull request #19 from gmjabs/headword

headword to master